## Centre of Gravity help please

Posted by John Shapp (207.172.233.148) on 01:39:57 12/12/04

Hi my name is John and I need help understanding how to calculate the center of gravity of the tube. Also if anyone has any tips on the design it would be greatly appreaciated.

I read something like w = m*g and w*cg = something but everything I read didn't make enough sense. I'm good with physics and math, but this is baffling me and with not much time left I need help.

Ok there are a few componets, the Mirror (a chunk of glass with an optical finish) A diagonal ( a small chunk of glass suspended in the middle of the tube by metal strips) and an eyepiece (focuses the light from the mirror into an image)

Ok the tube length is aproximately 36" (not fixed until the optics are done)

The mirror is at 1.5 lb's and 1.5" from the back which I am calling my reference. The diagonal is aproximately 1 pound and about 1" from the end of the tube. The eyepiece ( rides in a focuser, moves it in and out) is a total of about .5 pounds and is about 3" from the top.

I attached some picture so you get an idea. The tubes are going to be aluminum and the brown hex frames are plywood. I am not counting the weight of the aluminum and plywood yet, I figured it would be an even weight along the total tube, so it would just add weight and not affect the cg.

The middle two hex frames will have some sort of clamp, but they slide freely up and down the tubes to allow adjustment for cg.

If someone can please help me out with cg, even a simplified version of the formula, or steps.

( Goto assembled 1 and assembled 2 they show the thing. The other pictures are the mount and stepper motor being used)

Very much obliged,
John Shapp

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